Drawing polyester filaments using as a snubing means a heated roller driven at the feed rate speed

ABSTRACT

TURES THAT THE PERIPHERAL SPEEDS OF ALL FEED ROLLERS ARE SUBSTANTIALLY THE SAME AT LEAST THE LAST FEED ROLLER IS GIVEN A SMALL DIAMETER OF 15 TO 50 MM., AND THE ARC OF CONTACT OF THE FILAMENTS ON SAID ROLLER IS MADE AT LEAST 180, WHEREBY THE DRAWING POINT IS FIXED ON SAID ROLLER.   A PROCESS FOR DRAWING POLYESTER FILAMENTS WHICH COMPRISES DRAWING UNDRAWN FILAMENTS OF POLYESTER CONTAINING AT LEAST 85 MOL PRECENT OF ETHYLENE TEREPHTHALATE UNITS BETWEEN PLURAL HEATED FEED ROLLERS AND AT LEAST ONE DRAWING ROLLER ROTATING AT AT A PERIPHERAL SPEED HIGHER THAN THAT OF THE FEED ROLLERS, THE IMPROVEMENT RESIDING IN THE FEA-

NOV. 6, 1973 KAORU sAKATA ETAL $170,856

DRAWING POLYESTER FILAMENTS USING AS A SNUBING MEANS A HEATED ROLLERDRIVEN AT THE FEED RATE SPEED Filed Jan. 4, 1972 2 Sheets-Sheet 1 KaoruSakata Yosiharu Asada Yasuhiro Okamura INVENTORS ATTORNEYS Nov. 6, 1973KAORU SAKATA ErAL 3.170,866

DRAWING POLYESTER FILAMENTs USING As A SNUBING MEANS A HEATED ROLLERDRIVEN AT THE FEED RATE SPEED Filed Jan. 4, 1972 2 Sheets-Shoot 2 KaoruSakata Yosiharu Asada Yasuhiro Okamura INVENTO S ATTORNES United StatesPatent Olhce Int. (:1. Bz9c 17/02 U.S. Cl. 264-290 T 12 Claims ABSTRACTOF THE DISCLOSURE A process for drawing polyester filaments whichcomprises drawing undrawn filaments of polyester containing at least 85mol percent of ethylene terephthalate units between plural, heated feedrollers and at least one drawing roller rotating at a peripheral speedhigher than that of the feed rollers, the improvement residing in thefeatures that the peripheral speeds of all feed rollers aresubstantially the same, at least the last feed roller is given a smalldiameter of 15 to 50 mm., and the arc of contact of the filaments onsaid roller is made at least 180, whereby the drawing point is fixed onsaid roller.

This is a continuation-in-part application of Ser. No. 6,733, filed Jan.29, 1970, now abandoned.

This invention relates to a process for drawing polyesterfilaments. Moreparticularly, the invention relates to a process for drawing polyesterfilaments in which the drawing point is fixed, and filament breakage andwrapping of the broken filaments around the drawing rollers are reduced,the resulting drawn filaments exhibiting uniform tensile strength,uniform elongation and little fiuffs.

The most conventionally employed means for drawing polyester filamentscomprises the provision of a fixed heating means such as a heatedsnubbing pin or plate, between the feed roller and drawing roller, anddrawing the filaments by fixing the drawing point on said pin or plate.This method is quite effective when the denier of the filaments to bedrawn is light and the drawing rate is low, but when filaments of heavydeniers are to be drawn, it is difiicult to heat uniformly the entirefilaments across the cross-section, and consequently filament breakageand wrapping of the broken filaments around the drawing roller duringdrawing operation increase, which causes uneven distribution of physicalproperties and fluff formation in the drawn filaments.

Again, when the drawing rate is increased, the friction between thefixed pin or plate and the filaments passing thereon is also increasedto cause frequent filament breakage, rendering satisfactory drawingimpossible.

For this reason, it has been proposed to not use such fixed heatingmeans, but to employ plural, heated feed rollers, the filaments beingpassed on the rollers in zigzag form to be suificiently heated and drawnat high speed (British Pat. No. 874,652).

According to the above process, the defects in the firstmentioned methodare generally removed, but new problems such as shifting in drawingpoint, containing of undrawn portions in drawn filaments, wrapping ofthe broken filaments onto the drawing roller during drawing operation,occurrence of filament breakage and flufis, increase of unevenness intensile strength, elongation of the drawn filaments, etc. are broughtabout. Particularly, when undrawn polyester filaments of highpolymerization degree are drawn at high draw ratios in order to producehigh tenacity filaments, such shifting in drawing point re- PatentedNov. 6, 1973 duces the drawability, and drawn filaments having uniformproperties cannot be obtained.

The object of the present invention is to provide a process forefi'ectively drawing polyester filaments without using fixed heatingmeans, in which the drawing point is not mobile but fixed, and suchtroubles as drawing, monofilament coiling around the drawing roller,occurrence of filament breakage and fluffs, etc. are eliminated.

Another object of the present invention is to provide an economicallyadvantageous process whereby polyester filaments of heavy deniers can beeffectively drawn, free of the aforementioned drawbacks.

Still other objects and advantages of the invention will become apparentfrom the following descriptions.

We discovered that in drawing polyester filaments Without using a fixedheating means, filament breakage and wrapping of the broken filamentsaround the drawing roller during the drawing operation could beremarkably reduced and uneven tensile strength and elongationdistribution in the resulting drawn filaments could also be reduced byprovision of plural, heated feed rollers rotating at substantiallyidentical peripheral speeds, making the diameter of at least the lastfeed roller, i.e., the roller located the nearest to the drawing roller,15 to 50 mm., and contacting filaments on said roller to deflect atleast 180 of arc, whereby the drawing point is fixed on the last feedroller.

Due to the identical peripheral speeds, the smaller feed roll or rollsmust of course be positively driven rather than rotating freely.According to the present invention, the draw point of undrawn yarn isfixed effectively on the smaller diameter roll, and there is lessbreaking of the yarn by positively driving the smaller diameter roll andmaking the peripheral speed of the smaller diameter roll equal to thatof the large diameter feed rolls. If the peripheral speeds are notequal, for example if the smaller diameter roll is allowed to rotatefreely, the draw point varies and considerable yarn breakage occurs.This is shown later on in a comparative example. Such a defect can beobviated with the present invention.

Thus, the present invention is characterized in that, while drawingthermoplastic, synthetic filaments between plural, heated feed rollersrotating at substantially the same peripheral speed and at lease onedrawing roller rotating at a higher peripheral speed than the feedrollers, a small diameter, i.e. 15 to 50 mm., is given at least to thelast feed roller, and the filaments are contacted on said roller to bedeflected at least 180 of arc, to fix the drawing point on said roller.

We furthermore discovered that, in the above drawing process, if thequantity of finishing agent applied to undrawn polyester filaments isadjusted to less than that conventionally employed, such as 0.05 to 0.6%by Weight, the drawing point is still more accurately fixed on the lastfeed roller, and still better drawing can be performed.

Thus, in an embodiment of the present invention, undrawn filaments ofpolyester containing at least mol percent of ethylene terephthalateunits are drawn between plural, heated feed rollers rotating atsubstantially the same peripheral speed, and at least one drawing rollerrotating at a peripheral speed higher than that of the feed rollers, thequantity of finishing agent applied to the undrawn filaments is adjustedto 0.05 to 0.6 wt. percent, at least the last of the heated feed rollersis given a small diameter of 15 to 50 mm., and the filaments arecontacted on the small diameter roller to be deflected at least of arc,whereby the drawing point is fixed on said small diameter roller.

Although not critical within this range, the ratio of the diameter ofthe large feed rolls to that of the small feed rolls should be withinthe range 1.6-40z1.

During our research works, it was discovered that, particularly inmulti-stage drawing for making polyester filaments of high tenacity, amarkedly satisfactory result is obtained when the above-describeddrawing process is adopted for the first stage drawing, while making thesurface temperature of the small diameter roller 60410 C., and the firststage drawing ratio 2.5-5.5 times.

Thus, still in another embodiment of the present invention, undrawnfilaments of polyester containing at least 85 mol percent of ethyleneterephthalate units and having an intrinsic viscosity (calculated fromthe measured value in o-chlorophenol at 35 C.) of preferably at least0.75 are (a) drawn between plural, heated feed rollers rotating atsubstantially the same peripheral speed and at least one drawing rollerrotating at a peripheral speed higher than that of the feed rollers, thefinishing agent pick-up of the undrawn filaments is adjusted to 0.05 to0.6 wt. percent, at least the last of the heated feed rollers is given adiameter of 15 to 50 mm., the surface temperature of the small diameterroller is maintained at 60-110 C., the filaments are contacted on thesmall diameter roller to be deflected at least 180 of arc, and the drawratio is adjusted to between 2.5 and 5.5 times, and (b) thus drawnfilaments are further drawn by at least 1.1 times between said drawingroller and another drawing roller rotating at a peripheral speed higherthan that of the first drawing roller, whereby polyester filaments wellsuited for industrial use are provided.

Hereinafter the subject process will be explained, referring to theattached drawings in which:

FIG. 1 is a diagrammatic side view for illustrating the arrangement offeed rollers and drawing rollers in an apparatus used for practicing thepresent invention,

FIG. 2 is similar to FIG. 1, except that a finishing agentapplying meansis provided between the feed rollers and drawing rollers.

FIG. 3 is an explanatory drawing of the drawing mechanism of the subjectprocess, and

FIG. 4 is a diagrammatic side view showing the arrangement of variousrollers in an apparatus for practicing the multi-stage drawing inaccordance with the invention.

FIG. 1 shows an embodiment of drawing filaments with an apparatuscomprising plural, heated feed rollers and plural drawing rollers, inwhich the undrawn filament 1 is passed in zig-zag form on the fiveheated feed rollers 2a2e driven at a same peripheral speed and a smalldiameter feed roller 3 driven at the same peripheral speed as rollers2a-2e and heated to the same temperature level as of the feed rollers2a-2e, and the filament is then drawn by the four drawing rollers 4a4dwhich are driven at a peripheral speed greater than that of the feedrollers. The draw ratio normally ranges 3 to 7 times. In multi-stagedrawing, it is preferred to effect the first stage drawing at a drawratio of 2.5 to 5.5 times, and to make the total draw ratio 3 to 7times.

In the above embodiment, an oiling roller for applying finishing agent,etc. may be provided before the drawing roller 4a, as illustrated inFIG. 2.

According to the subject process, it is required that at least the lastroller 3 among the plural feed rollers is given a small diameter of to50 mm. as illustrated in the drawings.

When at least the last feed roller 3 in the heated feed rollers group isthus given a diameter of 15 to 50 mm., variation in drawing point ismarkedly reduced compared with the case of using a greater diameter feedroller. The reason may be explained with reference to FIG. 3. Generally,the tension in the filaments wound on a roller is expressed by 73:11, inwhich T U and T are respectively the tension in the filaments at theexit and entrance from and into the roller, ,1. is the frictionalcoefiicient between the roller and filaments, and 0 is the contact angleformed by the roller and the filaments. Therefore, the tensiondifferences AT at a smaller contact angle A0 is determined withoutregard to the roller diameter. Considering now two rollers of thediameter D and D respectively, the tension gradients in the filamentsbecome 2AT/D A0, and ZAT/D AG respectively, from FIG. 3. Thus, the lessthe diameter of the roller, the greater the tension gradient, and itbecomes possible to fix the drawing point at a constant position.

However, in case the last roller 3 of the heating and feeding rollersystem has a diameter less than 15 mm., the strength of the rollersystem is lowered and it cannot be used for a long time.

According to the subject process, it is furthermore required that theundrawn filament 1 must be contacted on the small diameter feed roller 3to be deflected at least 180 of arc.

If the arc of contact of the filaments on the small diameter feed roller3 is less than 180, even when the rollers diameter is not over 50 mm. asrequired, the drawing point cannot be fixed on said roller but is movedto the undrawn filaments-feeding side, to increase the occurrence offilament breakage and wrapping of the broken filaments around thedrawing roller, making the smooth drawing operation difiicult.

That is, in order to fix the drawing point to perform smooth drawing, itis necessary to use a small size roller of 15 to 50 mm. in diameter asat least the last feed roller, and to contact the filaments on said feedroller at least 180 of are.

When a small diameter heated feed roller as above is used, that rolleralone cannot sufficiently heat the undrawn filaments. Therefore, heatedfeed rollers must be provided preceding the small diameter roller orrollers to secure the sufficient heating of the filaments. Such can besecured by setting the contact time of the filaments with the surfacesof the heated rollers within the range of l to 10 seconds. In theembodiment of FIG. 1, plural feed rollers of relatively large diameters,such as above mm., are provided to effect sufficient heating. The smalldiameter feed roller is preferably provided close to the largerdiameter, heated feed rollers, preferably within the distance of 50 mm.,so as to prevent cooling of the filaments.

The surface temperatures to be given to the feed rollers are variabledepending on such factors as the type of polyester filaments to bedrawn, filament size, travelling speed of the filaments, etc., butgenerally temperatures around or over the second transition point of thepolyester forming the filaments are conveniently employed. Particularlypreferred temperatures range from 60 to (3., especially 65l00 C. Whenmany feed rollers are used, the feed roller group may contain a fewnumber of unheated rollers, so far as the sufiicient heating of undrawnfilaments is secured.

The surface of the small diameter feed roller is suitably given a mirrorsurface finish in order to prevent filaments from slipping thereon aswell as to fix a drawing point thereon, but in certain cases it may begiven a matte finish.

Only one, or plural drawing rollers may be used. All the heated feedrollers and drawing roller or rollers are suitably driven forcedly.

Furthermore, in the process of this invention, the finishing agentpick-up of the undrawn filaments 1 is preferably controlled to 0.050.6wt. percent to the Weight of undrawn filaments. Generally, in drawingsynthetic filaments 9. finishing agent is applied to the filaments to bedrawn, during the spinning or immediately before the drawing step, inorder to prevent accumulation of static charge and to improve filamentbundling property as well as drawability. The finishing agent pick-up onthe undrawn filaments is normally controlled to be at least 1.0 wt.percent in case of polyester filaments. However, in the preferredembodiment of the subject process, it is reduced to such minor amount asat most 0.6 wt. percent.

When the diameter of at least the last feed roller 3 is made 15 to 50mm., the arc of contact of the filaments on the small diameter feedroller at least 180, and the finishing agent pick-up onto the undrawnfilament from 0.05 to 0.5 percent by weight, the drawing point can befixed on the small diameter feed roller 3 with in creased certainty,compared with the case when more than 0.5 percent by weight of thefinishing agent is applied. Thus, the filament breakage and wrapping ofthe broken filaments around the drawing roller can be further decreasedto effect still smoother drawing. Accordingly, in this embodiment of theinvention, uneven distribution in tensile strength, and elongation ofdrawn filaments are also further reduced.

The type of the finishing agent to be applied onto the undrawn filamentsin the subject process may be any which has been conventionally employedin the spinning or drawing step of polyester filaments. Those finishingagents are applied to the filaments in the optional, conventionallyemployed form such as the oily state, emulsion, solution, etc., whilethe finishing agent pick-up referred to in the present specification isthe weight percent of the finishing agent itself, per the filamentsweight. In order to control the finishing agents pick-up to such minoramount as 0.05 to 0.6 wt. percent, either the finishing agent of thespecified amount is applied to the undrawn filaments, or the onceapplied excessive amount of finishing agent may be squeezed out of thefilaments preceding the drawing.

Since the finishing agent pick-up on the undrawn filaments is as littleas at most 0.6 wt. percent according to the invention, the drawnfilaments tend to accumulate static electric charge, exhibitdeteriorated bundling property, or form loops. Therefore, it is apreferred practice to apply a suitable amount of finishing agent to thefilaments after the drawing (in case of multi-stage drawing, after thefirst stage drawing) but before winding, to prevent occurrence of suchtroubles. The finishing agent to be applied onto the filaments afterdrawing is not necessarily the same as that applied to the undrawnfilaments. When polyester filaments for tire cord, belt cord, belt duck,etc., are to be drawn, epoxy compound, isocyanate compound, etc. may beapplied to the filaments at the optional point between the drawing andwinding, so as to improve their adhesion with rubber.

The subject process is particularly effective for multistage drawing ofundrawn filaments to make high tenacity filaments for industrial use.

FIG. 4 shows one example of such multi-stage drawing, in which theundrawn filament 1 is subjected to the first stage drawing between theheated feed rollers 2a- 2d, small diameter, heated feed rollers 3a, 3b,and the first stage drawing rollers 4a-4d. In that case it is necessaryto make the diameter of the small size feed roller 3b 15 to 50 mm., andthe arc of contact of the filaments on the roller 3b, at least 180.Furthermore, it is desirable to control the finishing agent pick-up onthe undrawn filaments 1 within the range of 0.05 to 0.6 wt. percent. Itis also necessary that the surface temperature of the heated feedrollers 2a-2d and that of the small diameter, heated feed rollers 3a,3b, should range from 60 to 110 C., and the first stage draw ratioshould range from 2.5 to 5.5 times (preferably 3.5-5.0 times). When thetemperature and draw ratio are out of the specified ranges, the fixingof the drawing point becomes imperfect and the filaments tend to breakand form fiuffs during drawing at the second and subsequent stages,failing to provide drawn filaments of uniform properties.

Then the first-stage drawn filaments are further drawn at least 1.1times, preferably 1.2-1.7 times, by second stage drawing between thefirst stage drawing rollers 4a- 4d and second stage drawing rollers7a-7j. In that case, the filaments are preferably heated toapproximately 120- 300 C. during the second. stage drawing. As theheating means 6 in FIG. 4, a slit heater is suitable for eliminating itsfriction with the running filaments to enable high speed drawing. Inorder to raise the atmospheric temperature in the slit to 120-300 C. asaforesaid, it is necessary to heat the heater itself to ZOO-400 C.Between the second stage drawing rollers 7e and 7f, an oiling roller 5for applying a finishing agent to the filaments is suitably provided.

Thus second-stage drawn filaments are then heattreated between thesecond stage drawing rollers 711-7 and driven rollers 9a-9e, in astretched, constant length, or shrunk state ranging from 1.2 to 0.8times the length before the heat treatment. The heating means 8 in thatcase may be a slit heater similar to that employed in the second stagedrawing. The atmospheric temperature in the slit ranges 120-300 C.

As already mentioned, it is desirable to use undrawn filaments ofpolyester having an intrinsic viscosity of at least 0.75, for producinghigh tenacity filaments by such multi-stage drawing.

The polyester undrawn filaments employed in the invention are composedof high molecular polyester containing at least mol percent, preferablymol percent, of a recurring structural unit of the formula,

The undrawn filaments may be those which are spun by optional spinningmeans conventionally employed.

Thus the term polyester is used in the specification and claims, in thesense including modified polyethylene terephthalate by the addition ofno more than approximately 15 mol percent of other ester-forming units.As such other ester-forming units, the following may be named by way ofexamples; diethylene glycol, other polymethylene glycol of 1-10 carbons,hexahydro-p-xylylene glycol; aromatic dicarboxylic acids such asisophthalic, dibenzoic, p terphenyl-4,4"-dicarboxylic, andhexahydroterephthalic acids; aliphatic acid such as adipic acid; hydroxyacid such as hydroxyacetic acid; and the like.

The properties of the undrawn filaments are not critical, but thefilaments having an intrinsic viscosity of at least 0.3, preferably atleast 0.75 and a birefringence rang ing 00005-00120 are preferred. Theundrawn filaments having a birefringence outside the specified rangetend to produce drawing failure or increase filament breakage duringdrawing operation. The density of the undrawn filaments is preferably nohigher than 1.35 g./cm. Otherwise the filament breakage during dravw'ngtends to be inreased.

Also the filaments to be drawn may have optional crosssectionalconfiguration, such as a circle and other modified forms. Again thesubject drawing process is applicable to any of multifilaments and towsfor staple fibers, while it is particularly effective for drawingundrawn filaments of heavy deniers such as above 2,000 deniers, at highdraw ratios.

According to the present drawing process, even with such heavy denierfilaments, the drawing point can be fixed. Consequently the resultingdrawn filaments have uniform tensile strength and elongation and littlefluffs, providing high quality products. Furthermore, filaments breakageas well as wrapping of the broken filaments around the drawing rollerare reduced to improve production efiiciency.

It is also possible in the subject process to parallel many strands offilaments and draw them simultaneously.

The values denoting the properties of polymer and filaments given in thespecification are measured as follows.

Intrinsic viscosity of a polymer is given as a norm of degree ofpolymerization of that polymer, which is defined below:

viscosity, obtained by dividing the viscosity of a dilute solution of apolymer by the viscosity of solvent employed which is measured at thesame temperature. Also is the polymer concentration in the solutionexpressed by g./ 100 cc. The intrinsic viscosities given in the presentspecification are calculated from the values measured at 35 C., usingortho-chlorophenol as the solvent.

It is well known that the load-elongation curve and breaking strengthand breaking elongation calculated from the curve are variable in shapeand value according to the length of test specimen and extension rate.In the present specification, the tensile test is performed with 20-cm.long samples at an extension rate of 50 percent/ min. under standardconditions (20 C., relative humidity of 65%), using an Instron tensiletester.

in FIG. 1 2a-2d was 250 mm, that of the feed rollers 2e and 3 was 20mm., and surface temperature of all the feed rollers was 70 C. The areof contact of the filaments on the feed roller 3 was 190. In this run,variation in drawing point was substantially nil as indicated in Table2, and excellent drawability was demonstrated. Furthermore, theresulting drawn filaments showed uniform tensile strength and elongationdistribution. However, when the diameter of the feed rollers 2e and 3was increased to 250 mm., the same size as the rest of feed rollersZa-Zd, in the manner of conventional practice, the variation in drawingpoint was notable, and uniformly drawn filaments could not be obtained.

TABLE 2 Amount of br oken filaments wrapped around EXAMPLE 1 Drawingpoint second stage Filament Strength Elongation variation range drawingroller 4 breakage distribution distribution (mm.) (g./hr.) (times/day)(g./de.) (percent) Subject process 0 0 0.3 9. (lit). 2 12. Oil). 5

Conventional process 2O 0. 4. 8 8. 35:0. 5 11. Oil). 7

EXAMPLE 3 Tows of polyethylene terephthalate undrawn filaments having anintrinsic viscosity of 0.62, birefringence of 526 l0- monofilamentdenier of 5 de. and total denier of 1,600,000 de. were drawn with theapparatus illustrated in FIG. 1.

The feed rollers Zia-2E each had a diameter of 300 mm. and surfacetemperature of 75 C., and the small diameter feed roller 3 was given asurface temperature of also 75 C., while its diameter and the arc ofcontact of the filaments on it were varied in each run. The draw ratioemployed in the experiments was 3.9 times, and the drawing speed was 100m./min. hTe finishing agent pick-up on the undrawn filaments was 0.5% byweight of the filaments.

The results were as given in Table 1 below.

Tows of polyethylene terephthalate undrawn filaments having an intrinsicviscosity of 0.65, birefringence of 632x l0 monofilament denier of 6.5de., and total denier of 1,600,000 de. were drawn with the apparatusshown in FIG. 1.

The feed rollers 2a-2e were each given a diameter of 300 mm. and surfacetemperature of 73 C., and the small diameter feed roller 3, a diameterof mm. and surface temperature of 73 C. The are of contact of thefilaments on the small diameter feed roller 3 was 190. The finishingagent pick-up on the undrawn filaments applied at the spinning step wasvaried in each run. The draw ratio was TAB LE 1 Amount of brokenfilament Drawing Diameter The are wrapped around point varia- FilamentStrength Elongation of roller 3 of contact drawing roller 1 tion range Ibreakage 5 distribution distribution (mm) (g./hr.) (mm.) (times/day)(g.lde.) (percent) Remarks gonvleptional process- 300 180 0. 24 =l:22 3.8 6. 105:0. 6 29. 81:4. 8 Control.

A 35 120 0. l9 3. 5 5. 90=l=0. 8 31. Di l. 4 Do. 13... 35 180 0 01 i2 06. 02=l=0. 2 30.4;i=1. 8 Subject process. C 35 540 0. 00 =|=1 0 5.95;l;0. 2 3t. Bil. 5 Do. D 45 120 0 12 3. 0 5. Wit). 7 30. 8:;4. 5Control. E... 45 180 0. 01 i5 0 6. 080. 3 29. 53:2. 0 Subject process.F. 45 540 0. 01 i4 0 6. 015:0. 2 30. 0=l:2. 3 Do. G 120 0 17 ..l=18 1. Z6. 00:1:0. 6 29. 9i3. 8 Control. H 55 180 0 12 $15 2. 0 6. 053:0. 4 30.63:4 0 Do. I. 55 540 0 13 5:12 1. 8 5. QBiO. 4 30. 8:1:3. 5 Do.

1 Amount of broken filaments wrapped around drawing roller means themeasured amount of the filaments broken and wrapped around the drawingroller during drawing operation expressed by the unit of gram per hour.

1 The drawing point. variation range was determined by naked eyeobservation.

5 "Filament breakage" denotes the fequeney of entire filament breakageduring drawing operation per day.

4 Drawing point shifted out of the small diameter roller.

Polyethylene terephthalate-adipate undrawn filaments (3.0 mol percent ofethylene adipate was copolymerized) having an intrinsic viscosity of0.80, birefringence of 200 l0- monofilament denier of 25 de., and totaldenier of 6250 de. were applied with 0.45% of a finishing agent, drawnby 4.2 times with the apparatus illustrated in FIG. 1, and further drawnby 1.4 times in a slit heater at 200 0, followed by a shrinkage of 5% ina 3.6 times, and drawing rate was 100 m./min. The results were as givenin Table 3 below.

TABLE 3 Finishing Amount of agent pick-up broken filaon undrawn meritswrapped Drawing filaments around drawing point varla- Filament Run (wt.roller tion range breakag e 0. percent) (g./hr (mm) (times/day) A 0. 50. 00 i2 0 B 0. 7 0. 04 i5 0. 8 C 1.0 0.08 :l:7 1.2

The above results clearly demonstrate that, by reducing the finishingagent pick-up on the undrawn filaments to not more than 0.6%, variationrange in drawing point is reduced and the filaments drawability can bemarkedly slit heater at 210 C. The diameter of each feed rollerimproved.

9. EXAMPLE 4 Polyethylene terephthalate-adipate undrawn filaments (3.0mol percent of ethylene adipate was copolymerized) having an intrinsicviscosity of 0.78, birefringence of 183 10- monofilament denier of 25de., total denier of 5840 de., and finishing agent pick-up of 0.45 wt.percent were drawn with the apparatus illustrated in FIG. 4. The feedrollers 2a-2d were each given a diameter of 250 mm., surface temperatureof 70 C., and the small diameter feed rollers 3a and 3b, the diameter of20 mm. and surface temperature of 70 C. The are of contact of thefilaments on the small diameter feed roller 3b was 540. The draw ratioin the first stage drawing was 4.3 times, that in the the resultingdrawn filaments showed little non-uniformity in tensile strength andelongation.

However, when the draw ratio in the first stage was selected outside thespecified range of 2.5-5.5 times, the drawing point could not be fixedon the small diameter feed roller 3b. Also when the surface temperatureof the feed rollers 2a-2d, 3a and 3b was selected outside the specifiedrange of 60110 C., the drawing point could not be fixed on the smalldiameter roller 3b, and objectionable wrapping around the drawingroller, fluff formation and filament breakage tended to occur morefrequently.

The results were as shown in Table 5 below.

TABLE 5 Amount of First Second Feed broken filaments stage stage Totalrollers Drawing Wrapped around draw draw draw surface po int secondstage Filament Strength Elongation ratio ratio rat1o temp. variationdrawing roller breakage distribution distribution Run No. (times)(times) (tunes) 0.) range (mm.) (g./hr.) (times/day) (g./de.) (percent)1 Drawing point shifted out of the small diameter roller.

second stage drawing was 1.4 times, and the temperature in the slit ofslit heater 6 was 200 C. Thus drawn filaments were then heat-treatedunder stretching to 1.05 times in a slit heater 8 heated to such a levelas will maintain the atmosphere in the slit at 200 C. during the thirdstage treatment. In this experiment the variation in drawing point wassubstantially nil as demonstrated in Table 4, and the filamentsexhibited excellent drawability. Furthermore, the resulting drawnfilaments showed little unevenness in tensile strength and elongation.

In contrast, when the diameter of feed roller 3b was increased over 50mm., or when the arc of contact of the filaments on the feed roller 3bwas reduced to less than 180, drawing point variation became remarkable,and uniform drawn filaments could not be obtained.

To show the necessity for positively driving the smaller diameter feedroll at substantially the same peripheral speed as the preceding feedrolls, the following experiment was conducted.

COMPARATIVE EXPERIMENT TABLE 4 Amount of The are of broken filamentDiameter contact of wrapped around of feed filamentson Drawingpointsecond stage Filament Strength Elongation roller the feed variationdrawin roller breakage distribution distribution 3b (mm.) roller 3brange (mm.) g./de.) (times/day) (g./de.) percent Remarks 20 540 0 0 0. 19. 1510.2 11. 9;};0. 4 Subject process. 20 150 5 0.09 3.0 8.9=|=0.4 11.91120.6 Control. 55 540 16 0. 12 3. 6 8. 7;l;0. 5 11. 5:|;0. 8 D0.

EXAMPLE 5 ratio employed was 4.0 and the drawing speed was 172Polyethylene terephthalate undrawn filaments having an intrinsicviscosity of 0.92, birefringence of 200x l0 monofilament denier of 21.8de., total denier of 5,430 de., and finishing agent pick-up of 0.40 wt.percent drawn with the same a paratus as employed in Example 4.

The surface temperature of feed rollers 2a-2d, 3a and 3b was 80 C., thearc of contact of the filaments on the small diameter feed roller 3b was190, the draw ratio in the first stage drawing was 4.0 times, that inthe second stage drawing was 1.4 times, and intra-slit temperature ofthe slit heater 6 was 200 C. Thus drawn filaments were heat-treated in aslit heater 8 which was heated to maintain the intra-slit temperature atthe third stage treatment m./min. The large and smaller feed rollers2a-2e, 3 were positively driven at a peripheral speed of 43 m./min. Thedrawn filaments were further drawn by 1.4 times in a slit heater at 200C., followed by shrinking by 9% in a slit heater at 210 C. On the otherhand, when a freely rotatable roller was employed instead of the smallerpositively driven feed roller, with the freely rotatable roller havingthe same diameter and temperature as the smaller feed roller, the drawpoint variation became remarkable, and objectionable wrapping around thedrawing rollers, fuzz formation, and filament breakage tended to occurmuch more frequently. The results are shown below.

TABLE Amount of broken filament Filament Draw point wrapped aroundbreakage Strength Elongation variation the draw (times! distributiondistribution Run N 0. Means for fixing the draw point range (mm.)rollers (g./hr.) day) (g./de.) (percent) Remarks A Positively drivensmaller feed roller- 0 0. 0 0 9. 0:1:0. 2 12. OiO. 5 Subject process. BFreely rotatable smaller roller '80 0. 5 4. 5 8. 55:0. 5 11. 05:0. 7Control.

The draw point was shifted toward the large feed rollers. at 210 C.,under a shrinkage of 3%. In the experiment, variation in drawing pointwas substantially nil, and the filaments exhibited excellentdrawability. Furthermore,

What is claimed is: 1. A process for drawing an undrawn polyesterfilament containing at least mol percent ethylene terephthalate unitswhich comprises feeding the filament between plural feed rollers ofsubstantially equal diameter with a surface temperature of 60-110 C. andpositively driven at substantially the same peripheral speed, contactingthe filament with at least one smaller feed roller, positively driven bymeans other than the filament at substantially the ame peripheral speedas the plural feed rollers and having a diameter of 15-50 mm. andtemperature of 60- 110 C., at an arc of at least 180, the ratio of thediameter of the plural feed rollers to the diameter of the smaller feedroller being between 1.621 and 40:1, and passing the filament onto atleast one drawing roller rotating at a peripheral speed higher than thatof the feed rollers to draw the filament at a draw ratio between 2.521and 5.5 :1, whereby the draw point is fixed on the last smaller feedroller.

2. The process according to claim 1, wherein 0.05- 0.6% by weight of afinishing agent is applied to the filament between the last smallerdiameter feed roller and the first drawing roller.

3. The process according to claim 1, wherein the undrawn filament has adenier value above 2,000.

4. The process according to claim 1, wherein the polyester ipolyethylene terephthalate.

5. The process according to claim 1, wherein the polyester has anintrinsic viscosity as measured in orthochlorophenol at 35 C. of atleast 0.75.

6. The process according to claim 1, wherein the undrawn filament is fedbetween the plural feed rollers in zig-zag form.

7. The process according to claim 1, wherein 0.050.6% by weight offinishing agent is applied to the filament prior to contacting thefilament with the first feed roller.

8. A process for drawing an undrawn polyester filament containing atleast 85 mol percent ethylene terephthalate unit which comprises feedingthe filament between plural feed rollers of substantially equal diameterwith a surface temperature of 60-110 C. and positively driven atsubstantially the same peripheral speed, the filament having a finishingagent thereon in an amount of 0.050.6% by weight of the filament,contacting the filament with at least one smaller feed roller,positively driven by means other than the filament at substantially thesame peripheral speed as the plural feed rollers and having a diameterof 15-50 mm. and temperature of -1 10 C., at an arc of at least theratio of the diameter of the plural feed rollers to the diameter of thesmall feed roller being between 1.6: 1 and 40:1, passing the filamentonto at least one drawing roller rotating at a peripheral speed higherthan that of the feed rollers to draw the filament at a draw ratiobetween 25:1 and 5.521, whereby the draw point is fixed on the lastsmaller feed roller, and further drawing the drawn filaments at least1.1 times between the drawing roller and another drawing roller rotatingat a peripheral speed higher than that of the first drawing roller.

9. The process according to claim 8, wherein the undrawn filament has adenier value above 2,000.

10. The process according to claim 8, wherein the polyester ispolyethylene terephthalate.

11. The process according to claim 8, wherein the polyester has anintrinsic viscosity as measured in ortho-chlorophenol at 35 C. of atleast 0.75.

12. The process according to claim 8, wherein the undrawn filament isfed between the plural feed rollers in zig-zag form.

References Cited UNITED STATES PATENTS 3,090,077 5/1963 Abbott 264-290 T3,539,680 11/1970 Fukushima et al. 264-290 T 2,918,346 12/ 1959 Paulsen264-290 T 3,433,008 3/ 1969 Gage 264-290 N FOREIGN PATENTS 864,5304/1961 Great Britain 264-290 R 903,027 8/1962 Great Britain 264-290 T874,652 10/1961 Great Britain 264-290 T 710,708 6/ 1954 Great Britain28-713 DONALD J. ARNOLD, Primary Examiner J. B. LOWE, Assistant ExaminerUS. Cl. X.R.

28-713; 264-Dig. 73

